Congrats on completing the 1/2! That's a tough distance to walk if you haven't gone more than 8 or 10 miles at one time before. You should look into racewalking if you want to improve your times. The racewalk techniques allow you to be more efficient and move faster. I've been doing it for about 1.5 years now and did my best 1/2 in 2:16 back in January (Carlsbad, CA). I usually pass a lot of jogger/walkers, as well as people who just jog slowly. Check out the racewalking sites below to learn a bit more. There aren't too many of us racewalkers out there at the big road races, but we do exist. If you're lucky, there's a group that meets in your area. Good luck on your next race!

http://www.philsport.com/narf/

http://www.racewalk.com/defaultRW.asp

http://members.aol.com/_ht_a/rayzwocker/worldclass/homepage.htm

http://www.walk2win.com/ - the group I belong to in San Diego